Got the thermo plastic sheet from work today. This is going to work out great I think. I will have pictures up tomorrow, should have some more work done on the tank.
are you using only that fibreglass as your sealer or are you doing an epoxy or epoxy paint overtop? what weight cloth are you using? curious about the thermosheeting as well.
We will be adhereing the thermo sheet to the plywood, sealing the corners with silicone, then using the fiberglass to completely seal the corners, making it a plastic lined plywood box......we hope
Are you sure the fiberglass resin will stick properly to the thermo sheet and to the silicone. It may just eat the sheet and not stick to the silicone. I would test this first.
I would try it the other way. Fiberglass the corners and rough up the resin when dry so silicone sticks to it. add thermo sheet and silicone.